The lightweight plastic ones are "Einweg" ("single use"), and the deposit is to get the material back for recycling - as long as the deposit label will scan, it's accepted. It's easier to scan them in the automats if they're not crushed; my German husband does not seem to have fully internalized this, so I reinflate them when they get rejected.

Glass bottles (beer, juice, milk and yoghurt) are "Mehrweg" ("multi-use"), and they actually want a bottle to sterilize and reuse (preferably with metal lid in the case of the milk and joghurt bottles), so if it's broken, it's technically trash and should go in the Altglas (old glass) containers you see at least once in every city neighborhood.